Priming systems are used to prime centrifugal fire pumps so as to reduce air pressure within an interior of the centrifugal pump. During priming, water is pushed by atmospheric pressure from a water source to the pump. Once water reaches the pump, the pump is able to provide continuous water flow and increase the pressure of the water without the aid of the priming system. In particular, the pump includes an impeller driven by a rotatable impeller shaft to deliver water from a pump intake to a pump discharge.
Current priming systems for centrifugal fire pumps include vane primers, piston primers, diaphragm primers and water ring primers. In some current implementations, the priming system draws power from the impeller shaft to prime the pump. In particular, an eccentric drive converts rotational motion from the impeller shaft to linear motion so as to increase water within the pump. To this end, a mechanism is utilized to engage and disengage priming systems from the impeller shaft. In one approach, a pump discharge pressure is monitored to physically engage and disengage the priming system based on water pressure within the discharge of the pump. Another approach involves housing the priming system remotely from the pump and driving the priming system by a belt or other suitable mechanical connection mechanism. Using this approach, the connection mechanism from the impeller shaft to the remote priming system is engaged and disengaged either by a clutch or by physically moving the priming system with respect to the connection mechanism.
For priming systems that rely on pump discharge pressure to engage/disengage the centrifugal pump, leakage through the priming system after the pump is primed can occur. To prevent leakage, an auxiliary mechanism is provided in order to control flow from the pump discharge to the priming system. The auxiliary mechanism increases cost and complexity to the priming system.
For priming systems that are remotely mounted and coupled to the pump, a separate housing for the priming system occupies space and increases complexity as the priming system needs separate accommodations within the truck. Additionally, the drive mechanism connecting the priming system with the centrifugal pump can generate noise and require guarding.